6 week Exam Review

That’s what makes our stars shine bright, bright, bright! What are stars? A star is a huge object in space made up of gas that gives off light and heat from nuclear reactions (fusion). Our sun is a star. Hydrogen Helium, Heat, & Light That’s what makes our stars shine bright, bright, bright! YAY! Fusion!

Earth’s nearest star is the Sun. The Sun is 150,000,00 km away! All other stars are light years away.

LIGHT YEAR A light year is the DISTANCE light travels in one year. We use this unit of measurement when measuring the distances between stars and galaxies. One light year is equal to 9.6 trillion km.

Life Cycle of a Star The changes that a star goes through is determined by how much mass the star has. Two Types of Life Cycles: Average Star- a star with relatively low mass (our Sun is low mass star) Massive Star- a star with relatively high mass

NEBULA All stars are born in a cloud of gas and dust called a nebula.

Nebulas, are “stellar nurseries”, places where stars are born. This is the Eagle nebula. You can see a star in the background. The weird shapes are clouds of gas forming new stars. All stars begin their lives in a nebula. The star life cycle. Link this cycle to the other cycles you have talked about in class.

We are here. Somewhere, in that mess of stars, planets, dust and gas We are here. Somewhere, in that mess of stars, planets, dust and gas. This is our galaxy, the Milky Way. What kind of galaxy are we? …..SPIRAL Our Sun is a medium sized star on one of the arms of the Milky Way. Our sun is NOT at the center of the galaxy. Scientists hypothesize that the center may be made of a massive black hole! We are a spiral galaxy. You could tell the kids that they can see the Milky Way if we have a really clear night and they get way out of the city.

Types of Galaxies: Spirals Spiral galaxies are so-named because of the graceful shapes of arms emanating from a bright central nucleus.

Types of Galaxies: Ellipticals Elliptical galaxies lack spiral arms and dust and contain stars that are generally identified as being old.

Types of Galaxies: Irregulars Irregular galaxies lack any specific form and contain stars, gas and dust generally associated with youth (They are “new” galaxies.

So, what is the force that holds galaxies together? Gravity

The Hertzsprung-Russell (HR) Diagram MAGNITUDE: Brightness Increases from bottom to top REMEMBER: Temperature Increases from right to left

The HR diagram shows the temperature and brightness of a star The HR diagram shows the temperature and brightness of a star. The hotter and brighter stars are located in the upper left of the graph. Our sun is average in its brightness and temperature.

The COLOR of a star indicates its temperature The COLOR of a star indicates its temperature. BLUE stars are the hottest. RED stars are the coolest. Our Sun is yellow, it is average in temperature.

SEASONS ARE CAUSED BY EARTH’S TILT!! This is a student model showing Earth’s tilt. The northern hemisphere is the getting direct sunlight, therefore it is summer.

NIGHT AND DAY IS CAUSED BY EARTH ROTATING ON ITS AXIS NIGHT AND DAY IS CAUSED BY EARTH ROTATING ON ITS AXIS. When THE PART OF EARTH is FACING THE SUN, it IS Day. ,

Phases of the Moon

Memorize each moon phase!

THE MOON The moon appears to change shape in the sky because of its position in relationship to the Earth and the Sun. The moon receives its light from the SUN!

TIDES are the periodic rise and fall of ocean water TIDES are the periodic rise and fall of ocean water. Rising water levels are called high tides, and falling water levels are called low tides

Why do we have tides?? The moon's gravitational force pulls on water in the oceans so that there are "bulges" in the ocean on both sides of the planet. The moon pulls water toward it, and this causes the bulge toward the moon. The bulge on the side of the Earth opposite the moon is caused by the moon "pulling the Earth away" from the water on that side.

SPRING TIDES create stronger tides SPRING TIDES create stronger tides. Tides are the strongest during a new moon or a full moon.

Neap tides are created during the quarter moons, the tides are weaker! Weaker Tides….